Commotio cordis is ventricular fibrillation after a direct precordial blow without mechanical damage to organs. Early recognition and prompt cardiopulmonary resuscitation with defibrillation save lives. According to previous reports, the major determinants of commotio cordis include location and timing of the blow. Other risk factors are young age, a thin and undeveloped chest cage, and a small hard spherical projectile. The pathophysiology of commotion cordis remains uncertain, such as individual susceptibility to prolonged repolarization and long QT.